The present invention relates to the general technical field of flexible heating elements composed of a heating circuit and means for establishing electrical connection with an exterior energy source.
The present invention concerns, more particularly, a flexible heating element, which is preferably flat, composed of at least one resistive wire defining a heating circuit inserted between two electrically isolating films.
Such a heating element can be utilized in all technical fields requiring the heating of bodies, which may be solid, liquid, or even gaseous, and the heating element according to the invention is not limited to any specific field of use. Preferably, the heating element according to the invention is more particularly intended to be integrated in a home electric appliance, and the invention concerns, to this effect, any home electric appliance containing a heating element according to the invention, and more particularly cooking appliances such as boilers and pressing irons, particularly steam irons.
It is already known to produce flexible heating circuits composed of a resistive element obtained, for example, by etching of a metal conductor. A resistive element which, for example, is based on an alloy of copper, tin or aluminum, is inserted, for example by a heat treatment under pressure, between two sheets, or films, of an electrical insulating material. The electrical insulating material can be composed of, for example, polyester, silicone glass, or even micanite. The resulting heating element possesses a certain flexibility, is generally substantially flat and can have any possible geometric form, including circular, rectangular, etc, selected on the basis of the desired utilization and installation conditions. In a standard manner, such heating elements are integrated into a structure or an apparatus in order to supply thermal energy and are provided, for this purpose, with means for connection to an energy source.
Up to the present, the electrical connections have always consisted, regardless of the specific application, of a series of isolated flexible wires and/or an assembly of isolated rigid metal bars connecting the circuit of the resistive element to the electrical energy supply source or sources. In a standard manner, the connection between the connecting wires and the circuit bars is effected by soldering, brazing or welding, preferably with tin, of the wire to the resistive circuit. For certain applications, it is possible to use conductive cements or even other types of soldering or brazing material such as electricians solder.
On the industrial level, and in particular in the case of fabrication of electrical home appliances, the use of a connector based on cables, wires or bars of the type mentioned above, which it is necessary to install on the electric home appliances, is time consuming and delicate and which therefore represents a non-negligible cost. Thus, it is generally necessary to precut the wires to the desired length, insulate them and possibly furnish them with terminals or lugs, and then proceed to the connection with energy supply or regulating units, followed by the soldering itself. This series of operations is difficult to integrate into an industrial fabrication process, in particular for the fabrication of home electric appliances such as pressing irons.